Decorating base metals or alloys of base metals



June 7, 1932. r c, McFARL-AND 1,862,231

DECORATING BASE METALS OR ALLOYS OF BASE METALS Filed June 22. 1928 k I p; Mi /Q 6.

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. jasefiafiz Patented- .lune 7, 1932 UNITED STATES PATENT oF Ic ,JmEs c. MCT'ARLAND, or roar THOMAS, KENTUCKY, assrenoa TO THE wanswon'rn WATCH CASE 00., OF DAYTON, KENTUCKY, A CORYOBATION OF KENTUCKY V DECORATING BASE METALS OR OF BASE METALS Application filed June 22, 1928. Serial No. 287,536.

The present invention relates particularly to a process for decorating base metals by means of contrasting metal platings, and is in the nature of a modification of the process described in application. Serial No. 287,535, filed of even date herewith.

I The primary object is to provide a very simple and effective method of decorating metals by means of platings of contrasting colors.

The process is well adapted to the purpose of decorating movement blocks. for example, employed in watches. Such a block may be composed of any suitable metal, such as what is known on the market as 12% nickel. The composition just referred to. is composed of about 12% nickel, copper, and 18% zinc. The process is applicable to other metals, or alloys of metals. however.

The process is illustrated in the accompanving drawing, in which-- a Fig. 1 illustrates a base plate having a resist design applied thereto: Fig. 2 illustrates a further step in which chromium plating is applied to the exposed areas of the base plate;

Fig. 3 illustrates a further step'in which the resist design has been removed. leaving exposed areas of the original surface and leaving the chromium plating desi n: Fig. 3A illustrates a further step in which the exosed areas of the base plate are etched: and

Fig. 4 illustrates a further step in which the exposed areas have been plated with a platable metal which is insoluble in ferric chloride. such as the precious metals or alloys thereof. I

In the illustration given in the drawing, A

designates a base plate which may be composed of a base metal. or an alloy of base metals; B designates a resist design applied to the surface of the base plate: C designates a chromium plating design applied to the exposed areas of the base plate: A designates exposed areas of the base plate produced by removing the resist; A designates etching on the exposed areas of the base plate; and

D designates a precious metal plating design applied to the exposed areas of the base plate. The surface of the plate, or body A, may

be of any desired cross-sectional contour, and may be polished, or pumiced, if desired.

The resist design may be applied in any desired manner. Preferably, it is applied by means of a photographic process, such as the one described in Beebe and Murray Patent 1,574,357, granted February 23, 1926.

In accordance with the method there described, a light-sensitive coating is applied to the original metal surface, and an image is produced in the sensitive coating photos graphically, or by means of light transmitted through a transparency bearing a suitable design; and the unreacted portions of the, 6

5 able developing operation, leaving upon the surface the reacted portions of the film in thesensitive coating are then removed by a suitform .of the desired design.

The exposed areas of the original surfaceq are now plated with a chromium plating;

the resist design is then removed by means. .of a suitable solvent, leaving exposed areas of the original surface and complemental areas covered by the chromium plating. Finally, the exposed areas of the original surface are plated with a plating of precious metal, such as gold, silver, platinum, or precious metal alloys.

The process results in a complete decorative design which comprises the chromium plating design and the precious metal plat ing design.

Chromium is an extremely hard, resistant metal having a color somewhat similar to the color of platinum, and the metal chromium will not tarnish. It may, therefore, be retained in the final decorative design, if desired.

Preferably the precious metal plating has a color which contracts with the chromium plating color. For example, a gold platin or a green gold plating, may be employed. If desired, the exposed base metal surfaces A, indicated in Fig. 3, may be etched by means of a suitable etching solution, such as ferric chloride, which will not affect the chromium plating. That is, the chromium plating may be used as a resist during the etching operation. Thereafter, the etched base metal areas may be plated with a precious metal. or precious metal alloy. The chromium plating will not receive the precious metal plating. On the other hand, chromium plating will be received readily by other metals. suitable current density per unit of area being employed in the plating operation.

If desired, after the base plate has received the plating of precious metal, the chromium plating design may be removed, for example, by using dilute hydrochloric acid or dilute sulphuric acid; and the exposed areas of the base plate may then be etched while using the precious metal plating (silver, for example) as a .resist. An etching operation of this character is more fully described in the above-mentioned application.

The improved method is applicable to producing decorative designs on various base metals and alloys, such as brasses, bronzes, German silvers, etc.

The foregoing detailed description has been given for clearness of understanding only, and no unnecessary limitations should be understood therefrom, but the appended claims should be construed as broadly as permissible, in View of the prior art.

What I regard as new, and desire to secure bv Letters Patent, is:

1. The method of treating a base metal surface, which comprises: applying tothe surface a suitable resist design; applying a chromium plating .design' to the exposed areas of the metal surface; removing the resist design, thus leaving areas of the original surface exposed and other areas covered by the chromium plating; etching the exposed areas of the original surface; and plating with precious metal said etched areas while the chromium serves as a resist.

2. A method of treating a base metal surface; which comprises: producing a chromium plating design on a portion of said surface and exposing the remaining areas; and plating said exposed areas with a platable metal of contrasting color, the chromium being used as a resist in the last-mentioned plating operation.

3. A method of treating a base metal surface, which comprises: producing a chromium plating design on a portion of said surface and exposing the remaining areas, and plating said exposed areas with' a metal comprising gold while the chromium plating design serves as a resist.

4. The method of treatin a metal surface, which comprises: pro ucing a. chromium plating design on a portion of said surface and exposing the remaining areas, etching those exposed areas with an etching solution which does not dissolve chromium plate; andlating the etched areas of the original meta while using the remaining chromium plate as a resist.

JAMES C. MoFARLAN D. 

